I have had an intermittent coolant leak for 6 months. I have gone through as many threads as possible to try things out, but nothing has worked. In that time I have just now gone through an entire container so the leak is small. I replaced the throttle body heater and associated hoses parts, new cap, new t-stat which was in fact causing a leak though still did not stop all the leaking. Pressure tested myself for 4 hours and no sign of leak and held pressure. Took it to a repair shop that pressure tested twice, did a leak down test, and drove around to try and replicate without luck. Finally took it to the LR dealer and they did not find anything to charge me for so I am at a loss. When I fill it back up it takes a week of driving to see if the level has fallen. Sometimes I may get a single drop on the ground directly underneath the engine. Even driving through heavy brush and dry creek in hot weather pulling a trailer with two calves the therm has never broken 215.

Any ideas?

 

Expansion tank and it's cap were checked out?
I would put uv dye in. Sounds like it may only be present at temp.the dye will help you find it if it's seeping at the head union or at a difficult location.

 

Have you tried an new expansion tank cap? All the tests would have been done with that cap off.

 

Some of these trucks seem to naturally bleed themselves down to around an inch below the FULL line on the expansion tank, and then they stop. It's weird, but several of us have noted this behavior.

 

The expansion tank is new and the cap is new as well. Is there a uv dye that works with the Dexcool? dr. Mordo I did read an earlier post where you mentioned some of them naturally bleed themselves down and then stay there. Where would the coolant be going if that is what is going on? Would it go out the overflow tube at driving temp when it expands? The lowest I let it go to check your idea was about an inch and a half left in the tank. Would that be too low for what you are suggesting?

 

Yea, mine does the same thing Mondo is mentioning. If I were you, I'd dump the Dexcool for standard green coolant, the Dexcool has a tendency to clog up and corrode stuff like the radiator, which could be why you're hitting 212. Mine never breaks 201 and usually stays under 198.

I'd say an inch and a half left in the tank is probably ok. Just from memory, that sounds pretty close to about an inch under the full line on the side.

 

I will ditch the Dexcool this week and see where that gets me. I have read on the forum several have used the zerex. The temp usually runs low 200. The one time it got up there I was pulling two calves across a dry creek on a 100 degree Texas September day.